Senators this week are slated to announce a bill they hope will curb foreign governments' influence on American elections.

Sens. Mark Warner, D-Va., and Amy Klobuchar, D-Minn., plan to announce a bill Thursday that aims to increase transparency in political ads, their offices said. Sen. John McCain, R-Ariz., will co-sponsor the bill.

Warner is the ranking Democrat on the Senate Intelligence Committee, one of the congressional panels investigating Russian efforts to influence the 2016 election and possible collusion with the Donald Trump campaign. Tech titans Facebook and Google parent Alphabet have said they found Russia-linked ads on their platforms during the election.

Should the bill gain traction, it would mark one of the first major efforts to rein in political advertising on platforms like Facebook.

"Russia attempted to influence the 2016 presidential election by buying and placing political ads on platforms such as Facebook, Twitter and Google," the senators said in a statement. "The content and purchaser(s) of those online advertisements are a mystery to the public because of outdated laws that have failed to keep up with evolving technology."

Twitter has found fake accounts and bots linked to Russia. The company has said it is taking steps to stop malicious bots and misinformation on the platform.

Warner added that users should know whether a story is trending because real people shared it or because bots or fake accounts engaged with it. He also wants campaigns to have the ability to see social media ads run for or against them, as they can with television and radio ads.

Officials from Facebook, Google and Twitter have been asked to testify at an Intelligence Committee hearing on Nov. 1.

Warner and Intelligence Committee Chairman Sen. Richard Burr, R-N.C., have said they expect Russia to try to affect the 2018 midterm elections.

Facebook is "open to working with lawmakers and reviewing any reasonable legislative proposals," a company spokesman said in a statement.

In a statement, a Twitter spokesperson said the company looks forward to "engaging with Congress and the [Federal Election Commission] on these issues."